Campbell said the carbon monoxide levels were about twice the lethal limit.

The bodies were found at a vacant home on the Reitnauer property in the 1500 block of Kumry Road.

District Attorney David Heckler has said Gary Reitnauer left a car running in an attached garage. He broke the garage door handle to prevent anyone from entering.

Michele Reitnauer discovered her husband's car and broke a window to help him. Heckler said Kimberly and then Jamie also died when trying to save their family.

Authorities have said they do not believe Gary Reitnauer had any intention of harming his family.

Jamie had contacted friends on her cellphone, saying she was worried about her father and wanted to call 911, but her mother objected, Heckler said.

Quakertown Community School District officials have said the sisters were bright students, both involved in many activities, including band and chorus. Kimberly was a junior at Quakertown Senior High School and Jamie was a fifth-grader at Trumbauersville Elementary.

Neighbors have said Gary and Michele Reitnauer worked at the same company in New Jersey and retired together, adopting the two girls.